Eli5: why are estimated budgets for big construction projects always wrong and end up spending more than expected? Why can’t we get better at these estimates?

Question

Eli5: why are estimated budgets for big construction projects always wrong and end up spending more than expected? Why can’t we get better at these estimates?

In: Economics

Answer 1

Prices are pretty much best case estimates (if not underestimated) because for public bidding the lowest price usually wins.

So there’s no incentive to be accurate if that puts you in the “too expensive” bracket.